Using Caché Objects - InterSystems Documentation

18
Method Generators
A powerful feature of Caché Object is the ability to define method generators: small programs
that are invoked by the Class Compiler to generate the runtime code for a method.
Method generators are used extensively within the Caché Class Library. For example, most
of the methods of the %Persistent class are implemented as method generators. This makes
it possible to give each persistent class customized storage code, instead of less efficient,
generic code. Most of the Caché data type class methods are also implemented as method
generators. Again, this gives these classes the ability to provide custom implementations that
depend on the context in which they are used.
You can use method generators within your own applications. A common usage is to define
one or more “utility” superclasses that provide specialized methods for the subclasses that
use them. The method generators within these utility classes create special code based on the
definition (properties, methods, parameter values, etc.) of the class that uses them. Good
examples of this technique are the %Populate and %XML.Adaptor classes provided within the
Caché library.
18.1 Defining a Method Generator
A method generator is simply a method of a Caché class that has its CodeMode keyword set
to “objectgenerator” :
Using Caché Objects 155